The International Consortium on Agricultural Biotechnology Research (ICABR)
Is marker-assisted selection cost-effectivecompared to conventional plant breeding methods? The case of Quality Protein Maize (QPM)
Kate Dreher, Michael Morris, Mireille Khairallah, International Maize and Wheat Improvement Center (CIMMYT), Mexico
Recent advances in biotechnology have led to the development of a number of novel tools that offer the promise of making plant breeding cheaper and faster. Among the most promising are molecular markers, which are segments of plant DNA that breeders use to detect the presence or absence in experimental plants of specific alleles of interest. By using molecular markers, breeders can bypass traditional phenotype-based selection methods, which involve growing plants to maturity and closely observing their physical characteristics in order to infer their underlying genetic makeup. Instead, breeders can rapidly determine inheritance patterns at the genomic level by directly examining the genetic makeup of experimental plants when they are still seedlings.
Proponents of biotechnology argue that marker-assisted selection (MAS) has the capacity to increase the efficiency of plant breeding significantly. It is hard to know if MAS will live up to its potential, however, because little empirical evidence is publicly available regarding the cost- and/or time-savings that are likely to be generated. The lack of economic data is particularly troubling to research managers in developing countries, for whom the decision whether or not to invest in biotechnology often depends critically on short-run financial considerations.
This paper reports the results of a case study conducted to assess the cost of using MAS relative to the cost of using conventional selection methods for a particular breeding application. The case study examined two breeding schemes designed to generate new Quality Protein Maize (QPM) lines. QPM lines contain a mutant form of the opaque2 gene that is associated with production in maize seeds of increased levels of lysine and tryptophan, two amino acids that play an important role in human and animal nutrition.
Detailed estimates were made of the costs of generating new QPM lines using conventional breeding methods versus the cost of generating new QPM lines with the help of MAS. Sensitivity analysis was carried out to identify factors that influence the relative costs of these two breeding strategies. The empirical results show how changes in the costs of fixed and variable inputs affect the cost- and time-savings that can be achieved through the use of MAS. They also suggest how the potential usefulness of MAS is likely to be affected by factors that tend to vary between breeding objectives (e.g., whether the trait being improved is monogenic or polygenic, whether the trait being improved is easy or difficult to observe at the phenotypic level).
Since no two breeding programs are exactly alike, strictly speaking our results apply only to the CIMMYT maize breeding program. However, our general conclusions are believed to be relevant to many other public plant breeding programs and should serve to highlight the circumstances under which MAS is most likely to offer advantages in terms of cost and/or time savings over conventional selection methods. Furthermore, our analytical approach provides a framework for carrying out additional case studies required to build up the body of empirical knowledge that policy makers will need to make informed biotechnology investment decisions.